JP2018187783A - Method of manufacturing thermoplastic resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a film which prevents metal elastic rolls from being scratched even when hard foreign matters are generated and which has few periodic defects due to the roll scratches.SOLUTION: The method of manufacturing a resin film includes molding by sandwiching and pressing a molten thermoplastic resin extruded from a die between a roll A and a roll B. The roll A is a metal elastic roll and the roll B is a rigid roll. Each of the roll A and the roll B has a surface processed layer which is a plating layer or a sprayed layer on the surface. The surface hardness of the roll A and the roll B in the Rockwell hardness test is 100 HR or more on M scale. In the Rockwell test, a difference (D (B) - D (A)) between the hardness D (A) of the roll A and the hardness D (B) of the roll B is 10 or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a thermoplastic resin film. In detail, this invention relates to the manufacturing method of the thermoplastic resin film using the roll apparatus used suitably for manufacture of the thermoplastic resin film by a melt extrusion method.

Acrylic resins are excellent in optical properties such as high transparency and low birefringence, and are therefore used as optical films and decorative films. In recent years, further improvement in film quality is desired in order to achieve higher definition of displays and higher design appearance of decoration. In particular, it is known that the surface state of the film is important for the film appearance, and high optical properties can be obtained with a film having good surface properties. In addition, a film with small thickness unevenness and high surface smoothness is excellent in adhesiveness with an adhesive layer or a printed layer in a subsequent process, and thus is expected to enhance the durability of the product.
As a method for improving the surface property by a forming method, a method in which a surface is generally pressed between mirror-finished metal rolls is known (Patent Document 1). However, when the thickness of the film is reduced, there is a problem that molding becomes difficult because the linear pressure becomes too large. In order to solve this problem, it has been proposed to use one metal roll as a metal elastic roll (Patent Documents 2 and 3).
As a method of finishing a metal roll into a mirror surface, plating surface processing represented by hard chrome plating is known as in Patent Document 4, and in Patent Document 5, production of a film using a roll sprayed with tungsten carbide is known. A method is disclosed.

Japanese Patent Laid-Open No. 7-1000096 JP 11-235747 A JP 2002-036333 A JP-A-11-105104 JP 2007-185938 A

  While it can be expected that high surface smoothness can be obtained by clamping with a mirror-finished roll, the roll surface may be scratched by foreign matter or gel generated during film formation to sandwich the film. The disadvantage that the scratches are transferred to the film and generated in synchronization with the rotation period of the roll is a serious problem. Particularly for optical films, in recent years, liquid crystal displays have been increased in size, and a film having a wide range and few defects has been demanded. If there are defects that occur in the rotation cycle of a roll, the liquid crystal display becomes a defective product. In the conventional method, both of the two rolls to be sandwiched are scratched, and there is a high possibility that the number of periodic defects twice as many as foreign substances will occur. In this case, since the metal elastic roll having a complicated internal structure is damaged, it has been a problem that the repair of the roll is very expensive.

  As a result of repeated investigations on the rolls to be used, these are rolls in which metal film processing is applied to metal elastic rolls and rigid rolls, the surface hardness of which is 100 HR or higher on the M scale in the Rockwell hardness test, and the hardness of the rigid rolls is metal A method for producing a film in which a metal elastic roll is less likely to be damaged when a hard foreign matter is generated by using a roll that is 10 or more larger than the hardness of the elastic roll, and has few periodic defects due to the roll damage. I found it.

  That is, the present invention relates to a resin film that is molded by sandwiching a molten thermoplastic resin extruded from a die between a first roll (hereinafter referred to as roll A) and a second roll (hereinafter referred to as roll B). In the production method, the roll A is a metal elastic roll, the roll B is a rigid roll, and both the roll A and the roll B have a surface layer processed layer that is a plating layer or a sprayed layer on the surface, The surface hardness of roll A and roll B is 100HR or more on the M scale in the Rockwell hardness test, and the difference between the hardness D (A) of roll A and the hardness D (B) of roll B (D (B) -D (A)) is 10 or more, It is a manufacturing method of the resin film characterized by the above-mentioned.

  Further, in the roll A, the outer diameter at a position of 1 cm from the roll end to the center side with respect to the outer diameter of the roll center may be 99.80% to 99.98%. It is more desirable that the difference from the outer diameter at the center of B is 1 mm or more.

  On the other hand, the thermoplastic resin preferably contains a (meth) acrylic resin, and the (meth) acrylic resin is a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate and an acrylate ester. It is preferable that it contains a coalescence.

  Furthermore, the thermoplastic resin desirably contains crosslinked rubber particles, and more desirably, the crosslinked rubber particles are an acrylate rubber polymer.

  The resin film may be an optical film or a decorative film.

Since the thermoplastic resin film produced by the production method of the present invention is sandwiched between two mirror rolls, the film thickness unevenness is small and the surface smoothness is high. Conventionally, this method has a problem that both of the two rolls are damaged when a hard foreign matter is generated, and the defect of the roll cycle due to the transfer of the scratches is increased. According to the present invention, since the metal elastic roll having a complicated internal structure and high re-polishing cost is not damaged, the disadvantage of the roll cycle is halved.
For this reason, the thermoplastic resin film produced according to the present invention has few defects that impair the appearance quality, and can be preferably used for optical applications and decorative applications for various products.

It is the schematic of the film extrusion film forming apparatus in this invention.

The structure in film production of the present invention will be described with reference to FIG. 1 as an example.
First, the thermoplastic resin is melted by the extruder 1, the molten resin is filtered by the polymer filter unit 3 via the gear pump 2, and discharged from the die 5 to the sheet shape via the static mixer (static mixer) 4. Then, it is sandwiched between the roll A6 and the roll B7 and formed into a desired thickness. Thereafter, the film is wound into a roll.
Hereinafter, it demonstrates in order.

<Extruder>
It does not specifically limit as an extruder used for this invention, Various extruders can be used. For example, a single screw extruder, a twin screw extruder, or a multi-screw extruder can be used. It is preferable to add a vent mechanism to the extruder in order to remove generated volatile components during melt kneading. As the screw, a full flight type screw, a barrier flight type screw or a screw with a mixing section can be used. The L / D of the screw 1 (L represents the cylinder length of the extruder and D represents the cylinder inner diameter) is not particularly limited, but in order to obtain a sufficient plasticization and kneading state, it is 10 or more and 100. Or less, more preferably 20 or more and 50 or less, and most preferably 25 or more and 40 or less. If L / D is 10 or less, it is difficult to obtain a sufficient plasticization or kneaded state. If L / D is 100 or more, excessive shearing heat generation is applied to the resin, and the resin may be decomposed.

  The cylinder temperature of the extruder is preferably 150 ° C. or higher and 310 ° C. or lower, and more preferably 180 ° C. or higher and 280 ° C. or lower. If the temperature is lower than 150 ° C., the resin is not sufficiently melted and unmelted foreign matter increases or the rotational torque of the screw becomes too large. On the other hand, when the temperature exceeds 310 ° C., the resin is thermally deteriorated, which leads to generation of foreign matters due to burns or gelation, and coloring of the resin.

<Gear pump>
The thermoplastic resin melted by the extruder is supplied to a gear pump in order to suppress pulsation of the extruder. The gear pump is adjusted to an amount of discharge corresponding to the amount of molten resin supplied from the extruder by inverter control.

<Polymer filter>
The polymer filter unit used in the present invention comprises two or more filter element portions for filtering resin and a housing portion into which molten resin is introduced and discharged.

The filter element may be either a leaf disk type or a cylindrical type. However, for the thermoplastic resin composition of the present invention to be described later, a cylindrical type in which shearing applied to the molten resin is relatively small is preferable.
Examples of the tubular filter element include tubular types such as a tube type and a candle type. Among these, a candle type filter element is preferably used.
As the filter medium, either powder sintering or fiber sintering can be used, and these can be combined.
The filtration accuracy of the filter in the filter element is usually 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 30 μm or less in consideration of the balance between productivity and foreign material size. A filtration accuracy of less than 5 μm is not preferable because thermal degradation is likely to occur due to shear heat generation of the resin. On the other hand, if it exceeds 50 μm, the ability to remove foreign substances is lowered, which is not preferable.

  In the polymer filter unit of the present invention, the angle formed by the intersection of the center line of the filter element and the center line of the single pipe to be merged is 20 ° or more and less than 60 ° in the resin joining portion after passing through the filter element in the outer portion of the housing. It is preferable that Thereby, the stay location by the resin flow rate difference can be suppressed, and a crowded defect can be reduced.

<Static mixer>
As a static mixer, use a static mixer that has a structure in which a large number of right elements with a square plate twisted 180 ° to the right and left elements with 180 ° twist to the left are arranged alternately in the pipe. Can do. By passing through each element of the static mixer, the action of division, conversion, and reversal occurs, and a further effect can be expected for uniformizing the temperature of the molten resin and uniforming the resin.

<Die>
The die is not particularly limited, and a conventionally known die can be used. For example, it is preferable to use a T die such as a manifold die, a fishtail die, or a coat hanger die. In order to stabilize the thickness, an automatic adjustment die that measures the thickness of the formed film and automatically adjusts the lip opening bolt is preferable.

<Forming roll>
The sheet-like molten resin extruded by the die is pressed between the first roll (roll A) and the second roll (roll B) arranged in parallel to each other and wound around the surface of the roll B. And molded.
<Roll A>

  The roll A used in the present invention includes a shaft member having a roll end plate, an elastic outer cylinder made of a thin metal having both ends attached to the shaft member via the roll end plate, and the thin metal A cooling fluid inflow space is provided between the outer cylinder and a metal inner cylinder accommodated in the same axial center in the thin metal outer cylinder. It is preferably a metal elastic roll formed by circulating a fluid. The elastic outer cylinder is an outer cylinder whose surface is elastically deformed according to the resin pressure. When a metal elastic roll is used for roll A, elasticity and rigidity can be optimized for thin-walled products. It becomes possible to obtain a good film appearance.

The surface of the roll A is coated by metal spraying and polished to a mirror surface. There is no restriction | limiting in the metal to spray, The material which consists of aluminum, titanium, chromium, tungsten carbide, cobalt, nickel etc. is used. Among them, a material made of tungsten carbide is preferably used from the viewpoint of hardness and surface smoothness.
The thickness of the metal sprayed layer for satisfying the requirements of the present invention is usually in the range of 50 μm to 400 μm, although it varies depending on the type of metal.

  The roll A preferably has a shape to which crowning is added in consideration of the deflection of the roll material. The crowning shape is a circular arc shape, and a shape in which the outer diameter of the roll end is 0.02 to 0.2% smaller than the outer diameter of the center of the roll is preferable from the adhesiveness of the entire film to be formed. More preferably, it is 0.05 to 0.15%.

Although there is no restriction | limiting in the material used for the said roll A, As material hardness, if it is 20 HS or more by Shore hardness, it is preferable, More preferably, it is 30 HS or more. When the hardness of the base material falls within the range, the indentation resistance after thermal spraying is improved, and the risk of damaging the roll due to foreign matter or the like is reduced.
<Roll B>

  As the roll B used in the present invention, a shaft member having a roll end plate, and a rigid outer cylinder made of thick metal on the outer peripheral portion of which both ends are attached to the shaft member via the roll end plate. A metal rigid body roll having a cooling space having a cooling fluid flowing in the inner peripheral portion is preferable. The rigid outer cylinder is not deformed by the resin pressure, and high film thickness accuracy can be obtained on the entire film surface by using a roll having high rigidity.

The surface of the roll B is coated by metal spraying or plating and polished to a mirror surface. There is no restriction | limiting in the metal used for thermal spraying or plating, The material which consists of aluminum, titanium, chromium, tungsten carbide, cobalt, nickel etc. is used. Of these, materials consisting of tungsten carbide and chromium are preferably used from the viewpoints of hardness and surface smoothness.
The thickness of the metal sprayed layer or the plated layer for satisfying the requirements of the present invention is usually in the range of 50 μm to 400 μm, although it varies depending on the type of metal.

  Although there is no restriction | limiting in the material used for the said roll B, As material hardness, it is preferable if it is 10HS or more by Shore hardness, More preferably, it is 20HS or more. When the hardness of the base material falls within the range, the indentation resistance after thermal spraying and plating is improved, and the risk of damaging the roll due to foreign matter or the like is reduced.

The roll B preferably has a taper shape that takes into account the thickness of the film end. As the taper, the taper ratio obtained by dividing (the outer diameter a at the center of the roll) − (the outer diameter b at the end of the roll) by the length L of the tapered portion is preferably 0.1 to 1.0%. Preferably it is 0.3 to 0.8%. Within the range, after the film is extruded from the die, the influence of the film end thickened by neck-in is reduced, and uniform contact with the roll can be obtained in the effective film width.
<Rockwell hardness test>

  The damage to the roll caused by sandwiching foreign matter generated during film formation occurs when the foreign matter is pressed against the roll surface with a large pressure. The Rockwell hardness, which is a conventional hardness index, was used as an index of the difficulty of scratching the roll in the present invention. Assuming that the foreign material is derived from a resin, an M scale used for evaluating the general plastic hardness was adopted.

  From the viewpoint of roll scratch resistance, Rockwell hardness needs to be 100 HR or higher, and preferably 105 HR or higher, for the thermal spraying of the roll B and the indentation resistance after plating.

  The difference D (A) −D (B) from the dent depth D (A) of the roll A obtained from the same evaluation is 0.1 μm or more. Since the indentation resistance of D (A) and D (B) is different, only one of the rolls is damaged due to the inclusion of foreign matter, which is advantageous in terms of cost including repair costs.

  The outer diameter Da at the center of the roll A is 300 mm or more, and the difference between the outer diameter Db at the center of the roll B, the outer diameter Da at the center of the roll A, and the outer diameter Db at the center of the roll B is preferably 1 mm or more. More preferably, it is more preferably 10 mm or more. By providing a difference in the outer diameter, it can be clearly seen which roll is damaged from the cycle of defects caused by roll scratches, which is preferable in terms of process management.

  The ratio (draw ratio) Va / Vb of the circumferential speed Va of the roll A and the circumferential speed Vb of the roll B is preferably 98% or more and 102% or less. More preferably, it is 99% or more and 101% or less. When the draw ratio is out of the range, the foreign matter defect is pulled on the roll, and an appearance defect due to the defect stretched in the flow direction occurs. Further, when the peripheral speed difference is further increased, scratches are generated on the film surface.

  The sandwiching pressure between the roll A and the roll B is preferably 10 N / mm or more and 60 N / mm or less as a linear pressure, and more preferably 20 N / mm or more and 50 N / mm or less from the viewpoint of the film surface.

<Thermoplastic resin composition>
The thermoplastic resin composition used in the method for producing a thermoplastic resin film of the present invention preferably has a melt viscosity of 100 Pa · s to 1500 Pa · s at 270 ° C. and a shear rate of 120 seconds− ^1, and 300 Pa · s to 1000 Pa. -It is more preferable that it is s. When the melt viscosity is 100 Pa · s or more, the back pressure is sufficiently large when passing through the filter device, and foreign matters can be effectively filtered. In addition, when the melt viscosity is 1500 Pa · s or less, the filter device can be prevented from being damaged due to excessive pressure applied to the filter device.
The melt viscosity can be measured by capillography or the like.

It does not specifically limit about the thermoplastic resin composition which can be used in the manufacturing method of the thermoplastic resin film of this invention. For example, polycarbonate resin such as bisphenol A polycarbonate; aromatic vinyl resin such as polystyrene, styrene-acrylonitrile copolymer, styrene-maleic anhydride resin, styrene-maleimide resin, styrene thermoplastic elastomer or hydrogenated product thereof; Crystalline polyolefins, transparent polyolefins with a refined crystal phase, polyolefin resins such as ethylene-methyl methacrylate resins; (meth) acrylic resins such as polymethyl methacrylate and styrene-methyl methacrylate resins; (meth) acrylic Heat-resistant (meth) acrylic resin modified by imide cyclization, lactone cyclization, methacrylic acid modification; polyethylene partially modified with polyethylene terephthalate, cyclohexanedimethanol, isophthalic acid, etc. Polyester resin such as terephthalate, polyethylene naphthalate, polyarylate; polyimide resin; polyether sulfone resin; polyamide resin; cellulose resin such as triacetyl cellulose resin; thermoplastic resin having transparency such as polyphenylene oxide resin; The containing thermoplastic resin composition can be used.
In the present specification, the (meth) acrylic resin refers to a methacrylic resin or an acrylic resin.
In consideration of actual use, it is preferable to select the thermoplastic resin composition so that the total light transmittance of the obtained film is preferably 85% or more, more preferably 90% or more, and still more preferably 92% or more. .

  Among the thermoplastic resins, a (meth) acrylic resin is preferable from the viewpoint of excellent optical properties, heat resistance, molding processability, and the like, and a thermoplastic resin containing 60 to 100% by mass of a methyl methacrylate unit is more preferable. A thermoplastic resin containing 70 to 100% by mass of the unit is more preferred, and a thermoplastic resin containing 80 to 100% by mass of the unit is most preferred.

  The (meth) acrylic resin may be a homopolymer of methyl methacrylate or may contain an acrylate unit. In the latter case, the methyl methacrylate unit and the acrylate unit may be contained in one type of polymer, or may be separately contained in two or more types of polymers. The content of methyl methacrylate units in the entire (meth) acrylic resin is preferably 60 to 100% by mass, more preferably 70 to 100% by mass, and further preferably 80 to 100% by mass. .

  Examples of (meth) acrylic resins include methyl methacrylate homopolymer (A), methyl methacrylate and acrylate copolymer (C), methyl methacrylate homopolymer (A) and acrylate ester. And a mixture of a homopolymer (B) of methyl methacrylate, a homopolymer of methyl methacrylate (A), a mixture of a copolymer of methyl methacrylate and an acrylate ester (C), and the like.

  The acrylic ester is not particularly limited, and examples thereof include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate.

The weight average molecular weight (Mw) of the (meth) acrylic resin is preferably 50,000 to 150,000, more preferably 60,000 to 150,000, and more preferably 70,000 to 100,000. Further preferred. The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the (meth) acrylic resin is preferably 1.7 to 2.6, and more preferably 1.7 to 2.3. Preferably, it is 1.7-2.0. By setting the molecular weight distribution to 1.7 or more, the molding processability of the thermoplastic resin composition is improved. Moreover, the impact resistance of the thermoplastic resin film obtained becomes favorable because molecular weight distribution shall be 2.6 or less.
In addition, a weight average molecular weight (Mw) and a number average molecular weight (Mn) are the values calculated by converting into the molecular weight of a standard polystyrene, analyzing by gel permeation chromatography (GPC).

  As the (meth) acrylic resin, those produced by known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization can be used. Among these, those obtained by the bulk polymerization method or the solution polymerization method are preferably used, and those obtained by the bulk polymerization method are more preferably used from the viewpoint of obtaining a thermoplastic resin film with few impurities.

  The content of the (meth) acrylic resin in the thermoplastic resin composition used in the method for producing a thermoplastic resin film of the present invention is preferably 70 to 95% by mass, and more preferably 75 to 90% by mass. Preferably, it is 80-85 mass%.

The method for producing a thermoplastic resin film of the present invention can be suitably used particularly for producing a thermoplastic resin film containing rubber particles.
Examples of the rubber particles include particles made of a polymer having units derived from an acrylate ester (hereinafter referred to as “acrylic rubber particles”), particles made of a polymer having units derived from a conjugated diene, and acrylic acid. Examples thereof include particles made of a polymer having a unit derived from an ester and a unit derived from a conjugated diene. In addition, these polymers may have a unit derived from a crosslinkable monomer as necessary. In particular, when a (meth) acrylic resin is used as the thermoplastic resin, the rubber particles are preferably acrylic rubber particles.

  The rubber particles are preferably rubber particles having a multilayer structure, and are rubber particles in which a plurality of layers are laminated substantially concentrically from the particle core to the outer shell, and the layers are bonded by graft bonding. Is more preferable.

The average particle diameter of the rubber particles is preferably 0.05 to 1 [mu] m, more preferably 0.1 to 0.5 [mu] m, and still more preferably 0. 0, from the viewpoint that the appearance defects of the resulting thermoplastic resin film can be significantly reduced. 1 to 0.3 μm.
Within the above range, two or more rubber particles having different average particle diameters may be used in combination.
In addition, the average particle diameter in this specification is an arithmetic average value in the particle size distribution on the volume basis measured by a light scattering method.

  The method for producing the rubber particles is not particularly limited, and can be obtained, for example, by emulsion polymerization of monomers constituting the rubber particles. The rubber particles having a multilayer structure are obtained by performing emulsion polymerization of the monomer constituting the innermost layer to obtain seed particles, and then sequentially adding the monomers constituting each layer in the presence of the seed particles. It can be obtained by successively polymerizing up to the outermost layer.

The rubber particle content in the thermoplastic resin composition used in the method for producing a thermoplastic resin film of the present invention is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, and 15 to 15% by mass. More preferably, it is 20 mass%.
When the content of the rubber particles exceeds 30% by mass, the heat resistance of the obtained thermoplastic resin film tends to be lowered, and when it is less than 5% by mass, the obtained thermoplastic resin film tends to become brittle.

The thermoplastic resin composition used in the method for producing the thermoplastic resin film of the present invention preferably contains various additives as necessary, preferably 0.5% by mass or less, more preferably 0.2% by mass or less. May be.
Examples of the additives include antioxidants, thermal deterioration inhibitors, ultraviolet absorbers, light stabilizers, lubricants, mold release agents, polymer processing aids, antistatic agents, flame retardants, dyes and pigments, light diffusing agents, and organic substances. Examples include dyes, matting agents, impact resistance modifiers, and phosphors.

Among the additives, it is preferable to use an ultraviolet absorber.
Ultraviolet absorbers are compounds that have the ability to absorb ultraviolet light mainly by converting light energy into heat energy. For example, benzophenones, benzotriazoles, triazines, benzoates, salicylates, cyanoacrylates, oxalic acid Anilides, malonic esters, formamidines and the like can be mentioned.
Among these, benzotriazoles and triazines are preferable, and benzotriazoles are more preferable from the viewpoint of suppressing deterioration of the optical properties of the thermoplastic resin film such as coloring due to ultraviolet irradiation. Moreover, oxalic anilides are preferable from the viewpoint of suppressing the yellowness of the thermoplastic resin film.

  Examples of the benzotriazoles include 2,2′-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] (manufactured by ADEKA; product Name: ADK STAB LA-31), 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol (manufactured by Ciba Specialty Chemicals; trade name TINUVIN329) 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (manufactured by Ciba Specialty Chemicals; trade name TINUVIN234) is preferable.

  Examples of the triazines include 2,4-bis (2-hydroxy-4-butyroxyphenyl) -6- (2,4-butyroxyphenyl) -1,3,5-triazine (manufactured by BASF; trade name Tinuvin 460), 2- (4- (2-hydroxy-3-2ethyl) hexyl) oxy) -2-hydroxyphenyl) -4,6-bis (2,4-dimethylphenyl) -1,3,5 triazine ( BASF Corporation; trade name Tinuvin 405), BASF Tinuvin 479, BASF Tinuvin 1477, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- [2- ( 2-ethylhexanoyloxy) ethoxy] phenol (manufactured by ADEKA; trade name ADK STAB LA-46), 2,4,6 tris (2-hydroxy-4-hexyloxy-3-methylpheny) ) -1,3,5-triazine (ADEKA Corporation, trade name ADK STAB LA-F70), and the like.

As the oxalic anilides, those having a maximum molar extinction coefficient ε _{MAX at} a wavelength of 380 to 450 nm of 1200 dm ³ · mol ⁻¹ cm ⁻¹ or less are preferable, and 2-ethyl-2′-ethoxy-oxalanilide ( Clariant Japan Co., Ltd .; trade name Sundebore VSU) is more preferred.
These additives may be added to the polymerization reaction liquid when producing the thermoplastic resin, or may be added to the thermoplastic resin produced by the polymerization reaction.

<Cyclical defects>
The “periodic defect” in the present invention refers to a foreign matter defect that occurs at the same position in the film width direction at a period that matches the roll diameter in the flow direction. The period here refers to the distance between defects when defects occur at the same distance in three or more consecutive foreign object defects. The “foreign matter defect” is a foreign matter detected by the difference in surface irregularities when viewed from the vertical surface of the film using the reflected light of a fluorescent lamp, and is a value of width (W) × length (L). Indicates a foreign material exceeding 0.10 mm ² .

<Application>
The use of the resin film of the present invention is not particularly limited. For example, vehicle decoration parts such as vehicle exteriors and vehicle interiors; building material parts such as wall materials, window films and bathroom wall materials; household goods such as tableware and toys; home appliances such as vacuum cleaner housings, television housings, and air conditioner housings Decorating parts; Interior members such as kitchen door covering materials; Ship members; Electronic communication devices such as touch panel covering materials, personal computer housings, mobile phone housings; LCD protective plates, light guide plates, light guide films, polarizer protective films, polarizing plates Examples thereof include optical films such as protective films, retardation films, front plates and cover materials for various displays, and diffusion plates; solar power generation members such as solar cells or panel covers for photovoltaic power generation.

  Among them, the film produced in the present invention is a member used for a display device such as a liquid crystal display device, for example, a polarizer protective film, a polarizing plate protective film, a retardation film, a brightness enhancement film, a liquid crystal substrate, a light diffusion sheet, It can use suitably for optical uses, such as a prism sheet. In particular, a polarizing plate protective film and a retardation film are more suitable.

  Moreover, the film of this invention can be used suitably for a decoration use. The decoration method is not particularly limited. For example, the resin film of the present invention is printed as it is or on at least one surface. A method of laminating the surface of the article to be decorated (lamination molding method); the resin film of the present invention is vacuum- or pressure-molded according to the shape of the article to be decorated, and then placed in an injection mold, and then injection molded A method of bonding simultaneously with injection molding by performing (insert molding method); injection molding by vacuum or pressure molding of the acrylic resin film of the present invention in an injection mold cavity, and then performing injection molding A method of laminating at the same time (in-mold molding method), a method in which the acrylic resin film of the present invention is placed along the surface of the object to be decorated in a vacuum state in a mold cavity, and then subjected to compressed air and press molding (vacuum / press molding) Pressure forming method, TOM forming method) and the like.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited thereto. In addition, the measurement or evaluation of the physical property value in an Example and a comparative example was performed with the following method.

[Foreign matter defects of film]
A 300-m roll film produced by the method described below was extracted 10 m from the end of winding, and the film was placed on a black flannel cloth under a fluorescent lamp (200 lux), and observed with reflected light. Mark the part where the reflected light appears to be different due to surface irregularities, and observe the part with a magnifying glass (PEAK 30 × manufactured by Tokai Sangyo Co., Ltd.). The width (W) × length (L) size is 0.10 mm ² or more. The foreign matter was observed.

[Presence of periodic defects]
Among the foreign matter defects observed by the above method, the distance between the defects is measured for three or more defects continuously generated in the flow direction at the same position in the film width direction. It was determined to be present. Further, by comparing the measured distance with the outer diameters of the rolls A and B, it was determined whether the roll A or the roll B caused a periodic defect.

[Production of rubber particles (A1)]
In a reactor equipped with a stirrer, thermometer, nitrogen gas introduction tube, monomer introduction tube and reflux condenser, 1050 parts by mass of ion-exchanged water, 0.3 part by mass of sodium polyoxyethylene tridecyl ether acetate and sodium carbonate 0.7 parts by mass was charged and the inside of the reactor was sufficiently replaced with nitrogen gas, and then the internal temperature was set to 80 ° C. Subsequently, 0.25 part by mass of potassium persulfate was added and stirred for 5 minutes. Further, 245 parts by mass of a monomer mixture consisting of 95.4% by mass of methyl methacrylate, 4.4% by mass of methyl acrylate and 0.2% by mass of allyl methacrylate were continuously added dropwise over 60 minutes. After completion of the dropping, a polymerization reaction was further performed for 30 minutes so that the polymerization conversion rate was 98% or more.
Next, 0.32 parts by mass of potassium persulfate was charged into the reactor and stirred for 5 minutes. Subsequently, 315 parts by mass of a monomer mixture consisting of 80.5% by mass of n-butyl acrylate, 17.5% by mass of styrene and 2% by mass of allyl methacrylate was continuously added dropwise over 60 minutes. After completion of the dropping, a polymerization reaction was further performed for 30 minutes so that the polymerization conversion rate was 98% or more.
Thereafter, 0.14 parts by mass of potassium persulfate was charged into the reactor and stirred for 5 minutes. Subsequently, 140 parts by mass of a monomer mixture consisting of 95.2% by mass of methyl methacrylate, 4.4% by mass of methyl acrylate and 0.4% by mass of n-octyl mercaptan was continuously added dropwise over 30 minutes. After completion of the dropping, the polymerization reaction was further performed for 60 minutes so that the polymerization conversion rate was 98% or more.
The latex containing the rubber particles (A1) obtained by the above operation was frozen and solidified, then washed with water and dried to obtain rubber particles (A1) having a three-layer structure. The average particle size of the rubber particles (A1) was 0.23 μm.

[Production of thermoplastic resin (B1)]
A thermoplastic resin (B1) having a weight average molecular weight of 80,000 was produced by bulk polymerization of a monomer comprising 100% by mass of methyl methacrylate.

<Example 1>
16 parts by mass of rubber particles (A1), 84 parts by mass of thermoplastic resin (B1) and 2 parts by mass of an ultraviolet absorber (Tinubin 460) were mixed with a Henschel mixer, and a biaxial shaft with a vent with a screw diameter of 75 mm set at 260 ° C The pellet of the thermoplastic resin composition was obtained using the extruder.
The pellets were melted using a single screw extruder with a vent having a screw diameter of 75 mm set at 260 ° C. The thermoplastic resin composition discharged from the extruder in a molten state is passed through a gear pump, a filter device, and a static mixer in this order, and formed into a film at a discharge rate of 120 kg / h from a T die having a lip width of 1850 mm and a lip opening of 1 mm. Extruded. The extruded film-shaped thermoplastic resin composition was sandwiched and cooled by two metal rolls to form a film having a thickness of 75 μm, and wound into a roll by a winder.
A metal elastic roll (roll A) having a Rockwell hardness of 123 HR and a surface of a base material having a Shore hardness of 30 HS sprayed with tungsten carbide having a thickness of 100 μm (WC sprayed in Table 1) as a metal roll to be used; The surface of the base material having a well hardness of 110 HR and a shore hardness of 20 HS was sandwiched and formed by a metal rigid roll (roll B) plated with hard chromium having a thickness of 110 μm (in Table 1, HCr plating).
The manufactured film was evaluated for periodic defects by the method described above. The results are shown in Table 1.

<Example 2>
As a metal roll to be used, a metal elastic roll having a Rockwell hardness of 122HR, a shore hardness of 30HS base material plated with hard chromium of 80 μm thickness, and a Rockwell hardness of 110HR, a base material of Shore hardness of 20HS. A film was obtained in the same manner as in Example 1 except that the surface was sandwiched and molded with a metal rigid body roll plated with hard chromium having a thickness of 80 μm.
The manufactured film was evaluated for periodic defects by the method described above. The results are shown in Table 1.

<Comparative Example 1>
As a metal roll to be used, a metal elastic roll having a Rockwell hardness of 98 HR and a surface of a base material having a Shore hardness of 30 HS plated with hard chromium having a thickness of 40 μm, and a base material having a Rockwell hardness of 95 HR and a Shore hardness of 20 HS A film was obtained in the same manner as in Example 1, except that the surface of the film was sandwiched and molded with a metal rigid roll sprayed with tungsten carbide having a thickness of 100 μm.

<Comparative Example 2>
As a metal roll to be used, a metal elastic roll having a Rockwell hardness of 95 HR, a surface of a base material having a Shore hardness of 20 HS sprayed with 50 μm thick tungsten carbide, and a base material having a Rockwell hardness of 110 HR and a Shore hardness of 20 HS A film was obtained in the same manner as in Example 1 except that the surface was sandwiched and molded with a metal rigid body roll plated with hard chromium having a thickness of 80 μm.

From the above results, it can be seen that the production method of the present invention was able to obtain a resin film having a good appearance with less dense defects per cm ^{2 and} less foreign matter defects and less black stripes.

1. Extruder, 2. 2. gear pump; Polymer filter, 4. 4. Static mixer Die, 6. 6. first roll (roll A), Second roll (roll B)

Claims (9)

A method for producing a resin film in which a molten thermoplastic resin extruded from a die is pressed between a first roll (hereinafter referred to as roll A) and a second roll (hereinafter referred to as roll B). The roll A is a metal elastic roll, the roll B is a rigid roll, and both the roll A and the roll B have a surface layer processed layer that is a plating layer or a sprayed layer on the surface, and the roll A and the roll B The surface hardness of the roll A is 100HR or higher on the M scale in the Rockwell hardness test, and the difference between the surface hardness D (A) of the roll A and the surface hardness D (B) of the roll B (D (B) -D ( A)) is 10 or more, The manufacturing method of the resin film characterized by the above-mentioned. The said roll A WHEREIN: The outer diameter of the position of 1 cm from the roll end with respect to the outer diameter of the roll center to the center side is 99.80-99.98%, The manufacturing method of the resin film of Claim 1 characterized by the above-mentioned. . The method for producing a resin film according to claim 1 or 2, wherein a difference between an outer diameter at the center of the roll A and an outer diameter at the center of the roll B is 1 mm or more. The manufacturing method of the resin film of any one of Claims 1-3 in which the said thermoplastic resin contains (meth) acrylic-type resin. The method for producing a resin film according to claim 4, wherein the (meth) acrylic resin contains a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate and an acrylate ester. The method for producing a resin film according to claim 1, wherein the thermoplastic resin contains crosslinked rubber particles. The method for producing a resin film according to claim 6, wherein the crosslinked rubber particles are an acrylate rubber polymer. The method for producing a resin film according to claim 1, wherein the resin film is an optical film. The manufacturing method of the resin film of any one of Claims 1-7 whose said resin film is a decorating film.

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